JPH022305Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a transmission for a sewing machine, and particularly to a two-speed taper clutch type transmission.

[Conventional technology]

An example of a tapered clutch type transmission device used in conventional sewing machines, such as cycle sewing machines, is shown in FIG. This figure is a cutaway sectional view of essential parts of an example of a tapered clutch type transmission that uses a flat plate clutch.

Since this conventional example is well known, detailed explanation will be omitted and an outline of the configuration/operation will be explained. F is a sewing machine frame (machine frame), and 31 is an upper shaft (main shaft), which is fixed to a drive pulley 43 with a tapered screw 34.
Reference numeral 12 denotes a support whose base portion is fixed to the frame, and an upper shaft 31 is loosely fitted into the cylindrical portion at the tip. 41 is a high speed belt on the high speed pulley 24, 49 is a low speed belt on the low speed pulley 48, 25 is a high speed belt on the high speed pulley 24
Cork disc for flat clutch fixed to,
26 is a switching clutch body of a taper clutch.

The ball bearing 23 on the drive pulley 43 has a clearance that allows it to slide a minute distance in the direction of the arrow a by a preload spring 38 in the shape of a corrugated disc.
is preloaded against the retaining ring 50 in the direction of arrow b. The outer ring of the ball bearing 23 is press-fitted into the high-speed pulley 24 and is constantly rotated by the high-speed belt 41.

In the low speed mode, the switching clutch body 26 and the low speed pulley 48 are brought into contact and integrated by the low speed spring 36, and the upper shaft 31 is rotated at low speed through the pawl clutch (not shown) between the pawl clutch body 27 and the drive pulley 43. However, in the high speed mode, the switching clutch body 26 is connected to the low speed spring 36 via the switching pulley 45.
The high-speed pulley 24 and the switching clutch body 26 are pressed in the direction of the arrow c with a force stronger than that of the high-speed pulley 24 and the flat plate clutch 25, and the high-speed pulley 24 and the flat plate clutch 25 contact each other, and the switching clutch body 26, high-speed pulley 24, The drive pulley 43 and flat plate clutch 25 are configured to rotate integrally and transmit high-speed rotation to the upper shaft 31.

[Problem that the invention attempts to solve]

Here, as is well known, the torque transmission force for the same axial pressing force between the taper clutch and the flat plate clutch 25 in the switching clutch body 26 is 1/(sinα+μcosα) for the taper clutch compared to the flat plate clutch. ) (Tazushi α: Taper angle, μ: Masatsu coefficient). moreover,
The spring pressure of the preload spring 38 acts on the negative side with respect to the flat plate torque, and conversely, the spring pressure on the tapered clutch side 26
It acts on the positive side.

Therefore, due to the large difference in transmission torque capacity between the taper/flat plate clutches, the torque difference/slip between the drive side and driven side of the pawl clutch (not shown) between the switching clutch body 26 side and the drive pulley 43 side is caused. There was a problem in that a vibratory rattling sound was generated between the respective claws due to the speed difference, which was accompanied by vibration and noise.

The present invention was devised by focusing on the problems of the conventional transmissions of this type as described above.
The purpose of this invention is to reduce vibration/chattering noise of the pawl clutch portion by using a low pressing force.

[Means for solving problems]

Therefore, in the present invention, the bearing and preload spring, which were conventionally arranged between the drive pulley and the high-speed pulley, are arranged between the high-speed pulley and the switching clutch body of the taper clutch. , which aims to achieve the above objective.

[Effect]

With the above configuration, the transmission torques of the tapered/flat plate clutches are equalized, and the torque vibration noise in the pawl clutch between the switching clutch body/drive pulley is reduced.

〔Example〕

The present invention will be explained below based on examples.

FIG. 1 is a cutaway sectional view of a main part of a transmission according to the present invention. Moreover, FIG. 3 is a schematic side view of the operating means. Moreover, FIG. 3 is a schematic side view of the operating means. In FIG. 1, the same or equivalent components as in FIG. 2 of the conventional example are, for comparison,
Represented by the same (equivalent) symbol.

(Structure) Embodiment E of the present transmission device replaces the ball bearing 23 disposed between the high speed pulley 24 and the drive pulley 43 in the conventional example FIG. Clutch body 27a
It is designed to be placed between the Accordingly, a wave-shaped disc-shaped preload spring 38 is also disposed at the illustrated position. Further, the pawl clutch (not shown) interposed between the driving pulley 43 and the pawl clutch body 27a remains unchanged, and a bearing B is provided between the switching clutch body 26, the pawl clutch body 27a, and the switching pulley 45a. is installed.

On the other hand, in the operating system shown in FIG. 3, a support stand 18 is built into the sewing machine frame F, and a switching pulley
A clutch lifter 9 that operates the clutch lifter 9 (FIG. 1) and the shutoff frame 5 are pivotally supported. 6 is a clutch switching cam having a cam shape 7 at the arm end;
is a cam follower roller of the clutch lifter 9, 20 is a high speed spring, 22 is a cutoff spring,
P is a starting pedal that operates the cutoff frame 5 via the lever device 51.

(Operation) In the above configuration, when the cutoff frame 5 is rotated in the d direction by stepping on the pedal P, the cam follower roller 8 rolls along the cam shape 7 of the switching cam 6 fixed to the cutoff frame 5. and cam shape 7 A
When the roller 8 falls into the position, the clutch lifter 9 is pulled in the direction of the arrow e by the high-speed spring 20, and with the clutch lifter shaft 9a as the fulcrum, the tip 10 of the clutch lifter 9 is pulled toward the switching pulley 45a.
(Fig. 1) and press the side of the switching clutch body 2.
6 on the support base 12, and the switching clutch body 2
6 pushes the high-speed pulley 24 fitted with the bearing 23 to the right in the figure via the integral pawl clutch body 27a to bring the flat plate clutch 25 and drive pulley 43 into direct engagement, and the tapered screw 34 The upper shaft 31 coupled with the upper shaft 31 is rotationally driven in a high speed mode.

(Function) As shown in FIG. 1, the switching pulley 45a is disposed on the support base 12 and further connected to the switching clutch body 26 and the pawl clutch 27a via a ball bearing B.

Since the preload spring 38 is interposed in the bearing 23 between the switching clutch body 26 and the high speed pulley 24,
This spring force is applied to the high speed pulley 24 and the flat plate clutch 2.
5 on the positive side, and vice versa between the switching clutch body 26 and the high speed pulley 24 on the negative side. Therefore, the amount of the spring is subtracted from the transmitted torque on the tapered clutch side, and this spring amount is added to the transmitted torque on the flat clutch side, so that the torque of both clutch portions is equally distributed to the pawl clutch portion 27a. This prevents the generation of vibration/noise between the pawls due to the difference in transmission torque as in the conventional example.

In addition, since torque can be efficiently transmitted as described above, the high-speed spring 20 for high-speed mode (Fig. 3)
Since the required torque of the flat plate clutch 25 can be maintained even if the torque is made weaker than before, the pressure applied to the starting pedal P can be reduced.

Furthermore, the reaction force of the high-speed belt 41 acting on the high-speed pulley 24 is borne by the support base 12 fixed to the frame F, and is directly handled as in the conventional example.
A secondary effect of not burdening the upper shaft 31 with a radial load can also be obtained.

[Effects of the invention] As explained above based on the examples,
According to the present invention, it is possible to equalize the transmission torques of the taper clutch section and the flat clutch section in the transmission of the sewing machine, thereby reducing the vibration/noise of the upper shaft driving pawl clutch section.

[Brief explanation of the drawing]

FIG. 1 is a cutaway sectional view of essential parts of a transmission according to the present invention, FIG. 2 is a diagram corresponding to FIG. 1 of a conventional transmission, and FIG. 3 is a schematic side view of an operating device. 23... Ball bearing, 24/48... High speed/high speed pulley, 25... Flat plate clutch, 26... Taper clutch switching body, 31... Upper shaft, 38... Preload spring, 43... Drive pulley, E... gearbox.

Claims (1)

[Scope of utility model registration request] A transmission device comprising a taper clutch switching body interposed between a low speed pulley and a high speed pulley, each disposed on the upper shaft of a sewing machine, and a flat plate clutch interposed between the high speed pulley and a drive pulley,
A transmission device for a sewing machine, characterized in that a bearing and preload spring means are interposed between the high speed pulley and the taper clutch switching body.